Taco shell forming and cooking method

ABSTRACT

A machine forms tortillas into cooked taco shells using a conveyor with a plurality of complementary, vertically extending forming elements which shift from a nested to an open condition as the conveyor sprockets are traversed for feeding and discharging the product. On the lower conveyor run the forming elements pass through a channel of cooking oil and then on to a station where cooked taco shells are discharged. A loading conveyor feeds tortillas in a spaced column towards the forming elements and an acceleration conveyor operates between the loading conveyor and forming conveyor for positioning the tortilla for engagement with a forming element.

This is a continuation of application Ser. No. 332,743, filed Dec. 21,1981, now abandoned.

This invention relates generally to food cooking and more particularlyconcerns an improved apparatus and method for forming and cooking tacoshells at high speeds by forming the tortilla starting material into apredetermined configuration and maintaining the material in thatconfiguration during the cooking operation.

Taco shell cooking mechanism of various types have been known and usedfor many years. Among the various devices which were employed are thosedisclosed in Saenz U.S. Pat. No. 2,603,143, Ford U.S. Pat. No. 2,967,474and Yepis U.S. Pat. No. 3,267,836. Each of these devices relates to ameans for forming and cooking a tortilla so that it may be used in thepreparation of tacos and similar food products. However, each of thedevices suffer from the disadvantage that either requires individualloading or has inherent capacity limitations, or may require an unduevolume of cooking oil or fail to meet the high standards for productuniformity required in contemporary production. The device disclosed inthe Sickles U.S. Pat. Nos. 3,880,065, 3,928,638, 3,785,273 and 4,154,153concern apparatus having a flexible, pliable belt deformed by a plungermounted transversely above the belt which clamps the tortilla againstthe belt forming a pocket in the belt. The mode of operation requiredintermittent belt action both when the tortilla was initially formed inthe pocket and when the tortilla was removed from the belt pocket whenthe plunger separated from the belt. An intermittent action was alsopresent as the pocket moved through the fryer. An improvement on theStickles concept minimized the intermittent motion by having a secondaryconveyor disposed in the fryer to convey the primary conveyor throughthe fryer during the fryer operation. This eliminated the intermittentmotion during that period. A further limitation of the Sticklesequipment was their dedication to a specific size of tortilla and theresulting taco shell. The machines were unable to accommodateinterchangeably tortillas of different diameters without substantialredesign. These machines, as well as that disclosed in Schy U.S. Pat.No. 3,570,393, were mechanically ingenious but were unduly complexmachines to fabricate, operate, maintain and clean. Consequently, theiradoption in most cases has been limited to applications where lowproduction may be tolerated in the range, for example, of from 75 to 325taco shells per minute.

Uniformity of product is a requirement in high volume commercialproduction of taco shells. This has been difficult to achieve withoutseveral operators at a visual inspection station positioned at thedischarge of the taco shell forming machine causing high labor cost foroperation. This, as well as a loss in scrap taco shells from rejectedproduct, was a negative influence in the overall economy of operation inthe prior art taco shell forming machines.

An important object of the present invention is to provide an improvedtaco shell cooking and forming apparatus or the like which is operableat a high production rate to produce a taco shell of improved qualitywith a minimum of imperfect taco shell rejects.

Another object of the invention is to provide an improved taco shellcooking apparatus or the like which is adaptable in design over a widerange both to use economically in a low production operation--say,production rates on the order of 75 to 150 units per minute, as well asin a high production operation, production rate for example, 350 to 750taco shells per minute.

Another object of the invention is to provide a taco shell cookingapparatus wherein the flat tortillas are formed into a U-shape about avertical plane co-extensive with the path of travel.

Another object of the invention is to provide an apparatus of the typedescribed, adaptable for forming taco shells from a variety of differentdiameters of tortillas.

Another object of the invention is to provide an improved taco shellforming and cooking apparatus which has a high density of productcontained within the mechanism when fully loaded, thereby achievingefficiencies in use of the cooking oil.

Another object of the invention is to provide an improved taco shellforming and cooking apparatus which operates economically at a highturnover rate of cooking oil, thus to achieve a lower free fatty acidcontent in the cooking oil absorbed by the product, giving a betterproduct shelf life by maintaining a high quality in the oil.

Still other objects of the invention will become apparent to thoseskilled in the field after having read the following detaileddescription of a preferred embodiment of the invention which isillustrated in the drawings.

In summary, the present invention comprises apparatus for shaping andcooking food products including a frame having thereon a vat containinga cooking medium through which the food product may be passed forcooking. An endless conveyor is arranged on the frame for carrying thefood product through the cooking medium and particularly from a productforming station to a product discharge station. The endless conveyorincludes a plurality of forming elements each having complementaryconcave and convex forming surfaces with the convex forming surfacebeing disposed on the leading edge of each forming element so that whenthe adjacent forming elements are disposed in a close togetherrelationship the mold surfaces are spaced apart so that the productinterposed therebetween is restrained, shaped and carried through thecooking medium. The forming station includes means for supplyingsheet-like food elements, one at a time, where each is engaged by theconvex surface of the forming element and carried in a downward curvefor enclosure within the concave portion of the preceding formingelement to be held therebetween during the cooking operation. Theproducts are discharged as the forming elements are spaced apart in anopen condition and the products are received on a support mechanism forremoval from the apparatus.

The method of the present invention is especially useful for forming ataco shell from a tortilla by preparing a spaced-apart procession oftortillas and moving them in a substantially flat plane. Thenaccelerating the tortillas individually to a forming station withoutchanging substantially their attitude. The tortilla is decelerated intosubstantially stationary condition wherein it is folded upon itself andsimultaneously moved in the folded condition in a path curved away fromthe flat plane and placed into a cooking medium and cooked to theproduct end point, and then removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of the taco shell forming and cookingapparatus of the present invention;

FIG. 2 is a plan view of the apparatus shown in FIG. 1;

FIG. 3 is a transverse sectional view taken in the direction of thearrows 3--3 of FIG. 1;

FIG. 4 is an enlarged detail view taken from FIG. 3 at the encircledportion;

FIG. 5 is an enlarged, fragmentary plan view in the direction of thearrows 5--5 of FIG. 1;

FIG. 6 is a fragmentary, sectional view taken in the direction of thearrows 6--6 of FIG. 5;

FIG. 7 is an enlarged sectional view taken in the direction of thearrows 7--7 of FIG. 5;

FIG. 8 is an enlarged fragmentary, developed view taken generally in thedirection of the arrows 8--8 of FIG. 2;

FIG. 8A is an end view taken in the direction of the arrows 8A--8A ofFIG. 8;

FIG. 9 is an enlarged detail view of the forming elements or molds ofthe present invention;

FIG. 10 is a plan view of the elements shown in FIG. 9;

FIG. 11 is an enlarged, fragmentary sectional view taken in thedirection of the arrows 11--11 of FIG. 1; and

FIG. 12 is an enlarged, fragmentary sectional view taken in thedirection of the arrows 12--12 of FIG. 2.

The high speed taco shell fryer 10 of the present invention is shown inthe drawings and referring particularly to FIGS. 1 and 2 includes aloading conveyor 11, a pan or vat 12 for containing a supply of cookingoil, product forming or loading stations 13, four endless conveyors 14,each equipped with a plurality of complementary forming elements 16 forcarrying the tortillas 17 from the forming stations 13 through the pan12 to an unloading station 18, it being understood the foregoingcomponents are suitably arranged upon a structural frame 19. Althoughfour endless conveyors 14, forming or laoding stations 13 and unloadingstations 18 are illustrated herein, the invention may be used with thesingle line of such components or with several conveyors 14 laterallycoupled together for conveying the product through the cooking medium.Although the cooking medium described herein is cooking oil, othercooking mediums may be practically used with this invention includingthose disclosed in U.S. Pat. Nos. 3,947,241 and 4,167,585 issuedrespectively on Mar. 30, 1976 and Sept. 11, 1979.

The tortilla carrying loading conveyor 11, shown in FIGS. 1, 2, 5 and11, includes an endless, flat, flexible wire belt 21 having provisionsfor maintaining and positioning the tortillas 17 in columns extending inthe direction of travel as shown in FIG. 2. These provisions include anarrangement in alternate wire elements (as shown in FIG. 6) of the belthaving outwardly projecting shoulders 22 as shown in FIG. 11. Theshoulders 22 are spaced apart laterally of the conveying path justslightly farther than the diameter of the tortilla, say 5 to 51/8inches. It is recognized that tortillas distort from the ideal diameterof design and take on a variety of eliptical shapes and sizes inordinary production. The present apparatus accommodates thesediscrepancies. When disposed between the wire shoulders 22 the tortillas17 will be maintained in alignment with the forming station as theloading conveyor 11 moves the product forward, to the right as seen inFIGS. 1 and 2. Product re-positioning means 23 serving to jiggle thewire belt 21 is shown in FIG. 11. The objective is to rock the wire belt21 laterally through the action of an adjustable eccentric 24 rotatablymounted on a shaft 25 driven by a variable speed motor 26. A clevis 27on the eccentric 24 is attached to a connecting rod 28 which extendsbeneath the top run of the wire belt 21 to an oscillating plate 29 whichwhen shifted back and forth in the direction of the arrows 31 imparts ajiggling or rocking action to the wire belt 21 to cause any tortilla 17which may be mispositioned and lodged upon a shoulder 22 (as indicatedby broken lines in FIG. 11) to slide into the space between theconfronting shoulders 22 and thus be properly positioned for receipt bythe product forming station 13.

The loading conveyor 11 is driven from a shaft 32 equipped with wirebelt engaging teeth 33 positioned along the length of the shaft 32,FIGS. 5 and 6. The shaft 32 is driven from a shaft 34 of a productacceleration conveyor 36 arranged in the product forming station 13,FIGS. 5 and 6. The shafts 32 and 34 are driven in the direction of thearrows as shown in FIG. 6 by means of a drive chain 37 reeved aboutsprockets 38 and 39 on the respective shafts 32 and 34 which are mountedin suitable bearings 41 secured to a frame member 42. Thus as shaft 32is driven in the direction of the arrow as indicated in FIG. 6, thetortillas 17 are moved from left to right as viewed in FIGS. 2 and 5 andthus advance in orderly rows towards the acceleration conveyor 36 to bedescribed more fully below.

It will be appreciated that the high speed taco shell fryer 10 may beconstructed and arranged to accommodate but a single column of tortillas17 wherein the conveyor belt 21 would be provided with but two pair ofshoulders 22 for defining a tortilla receiving channel. Or on the otherhand the taco shell fryer 10 may be designed and constructed to receivea plurality of rows of tortillas 17, there being four rows of tortillasillustrated herein. Noteworthy is that the present design is adaptableto form taco shells simultaneously in several rows without encounteringmechanical limitations associated with prior machines. The presentapparatus retains the qualities and advantages of the design whenemploying either a single row or several rows of tortilla formingmechanisms.

The pan 12 is essentially a vat for holding a supply of cooking oil 20maintained at the cooking temperature--on the order of 275° to 425°F.--by a system including a heat exchanger 43 and pump 44 driven by themotor 46 with the pump 44 circulating oil between the heat exchanger 43and pan 12 through a suitable piping system 47, FIG. 1. To achieveoperation with minimum volume of cooking oil 20 and thereby theadvantages of a high turnover rate of cooking oil which gives animproved quality of oil with lower free fatty acid values, the pan 12 isconfigured as shown in FIG. 3. This includes a plurality of channels 48which surround the forming elements 16 and through which the formingelements on the endless conveyor 14 are passed with one channel perconveyor system 14, as shown in FIG. 3. The channels 48 areinterconnected at each end to a header or manifold 49, FIG. 1, so that auniform flow of cooking oil may be maintained through each of thechannels 48 within the taco shell fryer 10.

The four endless conveyors 14 illustrated herein may be similarlyconstructed and as mentioned previously, this invention may be practicedthrough the use of only one endless conveyor 14 and in that situation inthe associated loading conveyor 11, pan 12, and forming or loadingstation 13 will be similarly adapted for the number of conveyors 14selected for use in the high speed taco shell fryer.

Referring specifically now to FIGS. 5, 6 and 8, the endless conveyor 14includes a drive shaft 51 driven through a drive chain and sprocketassembly 52 from a motor 53 coupled to a phase shifting device 55, theshaft 51 being suitably supported by pillow blocks or the like bearings54 mounted to the frame 19. To carry the forming elements 16 on theconveyor 14, the drive shaft 51 and the idler shaft 56 (FIG. 8) at theopposite end of the unit 10 are each equipped with two spaced apartdrive sprockets 57 to cooperate with two endless lineal drive elements,for example roller chains 58 for each conveyor 14. The forming orproduct carrying elements 16 are mounted to the pair of roller chains 58by means of a carrier 59 pivotally connected to the two roller chains 58by a pair of cross rods 61, FIGS. 4, 5, 8 and 9. Each carrier 59 isequipped to receive one cross rod 61 through the aligned circular holes62 in the tangs 64 and another cross rod through the elongated slot 63which telescopes over the tang portion of the "following" carrier 59having a similar pair of tangs 64 equipped with aligned opening 62, FIG.9. As may be seen from FIGS. 6 and 8, the sprockets 57 are of arelatively small diameter, say, on the order of 2 inches in diameter.The forming elements which pivot into an open condition as theirassociated cross rods 61 traverse the sprocket 57 at either the loadingor unloading station, extend outwardly from the axis of the sprockets 57a substantial distance, say, on the order of 81/2 inches. Thisrelationship between a sprocket of small diameter and forming elementshaving a substantial "arm length" provide the opening or "window" forloading a tortilla between consecutive forming elements 16 and forremoving a cooked tortilla or taco shell 170 at the unloading station,as shown in FIG. 8.

The forming or carrying elements 16 have a general shape of partiallyopened clam shells and individually are suitably secured to theirassociated carriers 59 as by welding. Each forming element 16 includes afirst body 16a having a generally vertically arranged convex formingsurface 66, FIG. 9, and a second body 16b having a concave formingsurface 67. The two bodies 16a, 16b are fixedly secured together bywelding and arranged as shown in FIG. 9. The trailing edge of the body16b is curved so that as the forming elements 16 proceed through theforming operation as shown in FIG. 6, the trailing edge as curvedprovides the maximum "window" for insertion of the tortilla. Referringto FIGS. 9, 10 and 12, the forming elements 16 are so shaped that whenthe carriers 59 of consecutive elements 16 are arranged so that thealigned holes 62 and slots 63 are disposed substantially in the sameplane, there is a product enclosing space provided between the concaveforming surface 67 on the forward carrier and the convex forming surface66 on the trailing or following carrier. This space between theconfronting forming surfaces 66, 67, serves to receive and enclose atortilla to hold it in the folded condition when it is carried throughthe cooking oil 20. The space between the confronting forming surfacesis slightly wider than the thickness of the tortilla and the formingsurfaces are such that the tendency of the product to slide out from theslot or space is minimal due to good surface contact and productbuoyancy in the cooking oil 20. It is also apparent that a plurality ofapertures 69 are provided in the forming elements 16a, 16b, affordingaccess of the cooking oil to the product as well as to provide escape ofwater vapor from the product in the cooking operation. Cooking with theproduct vertically oriented promotes rapid escape of steam and minimizestrapping of moisture vapor and consequent product blistering.

Track means 70 are provided on the tortilla shell fryer 10 formaintaining consecutive forming elements 16 in the nested or closedrelationship by restraining movement of the roller chain 58 to which thecarriers 59 are connected through the cross rods 61, best shown in FIGS.4 and 12. More specifically, the track means provided for each of thetwo roller chain sets 58 is a vertically spaced pair of bars 71 defininga guide slot 72 therebetween into which the roller chain links 58 travelfrom the forming station 13 to the unloading station 18. When the rollerdrive chains 58 are freed from the guide slot 72, as when the sprockets57 (FIGS. 6 and 8) are traversed by the roller chain and carriers 59,the forwardmost forming element 16 accelerates as it reaches a point oftangency to the sprocket 57 at a moment when the following formingelement 16 remains at the linear speed of the roller chain 58. At thismoment the forward carrier 59 and its forming element 16 move away fromthe trailing carrier 59 and its element thus at the unloading station 18exposing on the convex forming surface 66 a cooked tortilla now a tacoshell 170 (FIG. 8). The elongated aperture or slot 63 in the carrier 59permits the cross rods spacing to become shorter so as to accommodatethe movement of the carriers over the sprockets 57 at each end of theconveyor 14.

Considering at this time the discharge or unloading station 18 as shownin FIG. 8, means are provided to ensure that the taco shell 170 ispositively disengaged from the convex forming surface 66. To this endthere is arranged on each side of the unloading station a power drivenunitorarray 74 of bristle-like or finger-like elements 78 mounted on theframe 19 with each unit 74 being driven by an electric motor or the likein the direction of the arrows 77 as indicated in FIG. 8A. The bristleelements 78 provide sufficient frictional forces to firmly but gentlyurge the taco 170 in a forward but downward direction so that a tacoshell 170 may be received upon the fixed conveying member 79 for removalonto the discharge conveyor 81, as shown in FIG. 8. Alternatively, acompressed air jet arranged at the unloading station 18 (not shown)could serve to actively disengage the taco shell 170 from the convexforming surface 66. A pan 82 is provided at the discharge or unloadingstation 18 to return any oil drippings from the taco shell 170 andconveyor 14 back into the cooking vat 12. The drip pan 82 is positionedjust below the product conveyor 14 and also acts to ensure thattortillas/taco shells do not fall from the enclosure defined by theforming elements 16 should this event for any reason occur.

A guide bar 86, FIG. 6, positioned at the forming station 13 below thelower run of the conveyor 14 serves to limit downward movement of anytortilla which may for some reason project below the lower perimeter ofthe forming elements 16. Thus, the provision of the bar 86 and the pan82 obviates the possible clogging or contaminating the cooking medium 20from product dropping into the cooking oil. It has been observed thatthe buoyancy of the tortilla in the cooking oil assists in retaining thetortilla between consecutive forming elements in the formed condition.

The details of this forming or loading station 13 are shown in FIGS. 5through 7. Provisions are included to ensure that each tortilla 17transfers onto the product acceleration conveyor 36 in a direct,positive manner and to this end coacting pairs of acceleration rolls 90,91 for each conveyor 14 are arranged on shafts 92, 134 at the terminalor turnaround portion of the loading conveyor 11, best shown in FIG. 5.The upper and lower acceleration rolls 90, 91 are spaced apart laterallyso as to grip the central portion of the tortilla 17, moving it in astraight line onto the acceleration conveyor 36 which maintains andcarries the tortilla in accelerated motion until finally the tortilla isarrested by the spaced abutments or stops 93. These project verticallyupward from alongside the acceleration conveyor chains or belts 94 andserve to position and maintain the tortilla 17 centered for the ensuingoperation. This obviates taco shell "longhorns" where the shells areformed unsymmetrically, one side being longer than the other. Theacceleration rolls 90, 91 and the product acceleration conveyor 36 aredriven from the shaft 51 of the product forming conveyor 14 through adrive chain 96 which reeves over sprockets on the shaft 92, FIG. 6. Anidler sprocket assembly 97 maintains the chain 96 at proper tension. Theproduct acceleration conveyor 36 is driven from shaft 92 through a drivechain 98 which reeves at the lower portion over an idler sprocketassembly 99. The pair of flexible belts 94 of the product accelerationconveyor 36 reeves through sheaves 101 on an upper cross shaft 102 andruns downwardly to a lower cross shaft 103 carrying sheaves 104. Asshown in FIG. 7, each belts 94 is supported vertically by a track 106 todefine precisely the plane of the belts 94 at the forming station. Thecross shafts 102, 103 are supported by a U-shaped sub-frame 107 securedto a cross member 108 which forms a component of the framework 19, FIG.6.

A guide chute or cavity 111 is arranged in each product forming orloading station 13 to receive therein the procession of forming elementsand tortillas as the forming elements 16 and their associated carriers59 proceed downwardly when the carriers 59 traverse the outer peripheryof the sprocket 57, FIG. 6, in the turnaround mode. The consecutiveforming elements 16 at turnaround separate to an angular displacement ofabout 86°, leading edge to leading edge of the forming elements 16 asshown both in FIG. 6 and in FIG. 8. Referring specifically to FIG. 6, agap of about 33° exists between the trailing edge of the forming elementshown in the lower portion of the drawing and the leading edge of theforming element about to engage the tortilla 17. The available time forthe tortilla to arrive at the loading position prior to forming is 0.225seconds with the product conveyor 14 speed at 200 inches per minute.

It has been found desirable to restrain and control the downwardmovement of the tortilla as it is urged downward and formed against theconvex forming surface 66. To this end, the guide chute or cavity 111 isequipped with restraining means comprising an array of bristle-likeelements 116 disposed on each side of the vertically downward movingforming element 16, the free ends of the bristles being spaced apart adistance slightly less than the width of the forming element 16. Thus,the nose of the descending forming element urges the tortilladownwardly, as indicated in FIG. 7, into contact with and against thebias of the bristles 116 as the tortilla is moved into the concaveforming surface 67. Subsequently the consecutive forming elements areheld together in proper forming condition for shaping a taco shell fromthe tortilla as the associated carrier cross rods 61 enter the guideslot 72 with the chains 58. The bristles or brush-like elements 116prevent the tortilla 17 from free falling into the guide chute or cavity111 and so maintain control of the descent of the tortilla being urgedinto the guide chute or cavity 111 by the convex portion of the formingelement. A spaced pair of stationary rods 117 extend longitudinallyalong the top portion of the guide chute or cavity 111 and establish acontour or guide surface for the descending tortilla 17. The surface ofthe rods 117 act effectively to relieve the tortilla almostsimultaneously from the acceleration belt 94 upon engagement of thetortilla by the nose or leading portion of the forming element 16. Thisaffords additional control to the descending motion of the tortilla.

To operate the high speed taco shell fryer 10 and produce 100 finishedtaco shells per minute per product conveyor 14 the operator first bringsthe body of oil 20 contained in the pan 12 to the desired operatingtemperature for example in the range of 275° to 425° F. The tortillacook time is about 30 seconds. The heat exchanger 43, pump 44 and motor46 are energized to realize the desired temperature of the oil 20. Theprincipal drive motor 53 is actuated to set into motion the severalconveyors of the unit 10, including the product conveyor 14 which movesat 200 inches per minute carrying 162 elements 16, the loading conveyor11 which moves at 600 inches per minute, the product accelerationconveyor 36 and the acceleration rolls 91 which move at 1,500 inches perminute, FIGS. 5 and 6. The tortilla re-positioning mechanism 23 isactuated to impart general side-to-side action to the conveyor belt 21for lodging any mispositioned tortilla 17 between the spaced apartshoulders 22 which define the channels on the wire belt 21 in which thetortillas 17 are conveyed towards the forming station 13.

The 5 inch diameter tortillas 17 are regularly spaced at about 6 inchcenters in rows on the wire belt 21 starting from a designated orindexing wire belt element (not shown), but the spacing is not criticalin this system because of the speed relationships between theacceleration conveyor 36 and the product conveyor 11 which coordinatewith the forming conveyor 14 in a manner such that the variation inspacing between adjacent tortillas 17 may be on the order of plus orminus 1 inch from the 6 inch pitch. The phase shifting device 55 may beactuated to ensure that the product conveyor 11 receives tortillas 17from the tortilla forming apparatus (not shown) properly timed for theoperation of the high speed taco shell forming unit 10. The speed of theacceleration rolls and accelerating conveyor 36 ensures that a tortillawill be lodged at the forming station 13 as the forming elementsapproach the guide chute or cavity 111 to commence the taco shellforming operation. Mentioned above was the gap between successiveforming elements 16 (in the loading position) at the product formingstation 13 and in terms of time this was about 0.225 seconds. This gaphas been found sufficient to permit accurate lodging of the tortillaagainst the abutments 93 to be carried downwardly in a curved path intothe concave forming surface 67 disposed therebelow.

Once the successive forming elements 16 go into the "nested" or "closed"relationship they are maintained in a relationship tending to hold thetortilla by reason of the drive chains 58 and cross rods 61 beingcarried smoothly in the slot 72 of the spaced apart tracks 71 as theendless conveyor 14 traverses the oil containing channels 48 in the pan12. The tracks 71 are directed through a gentle curve downwardly throughthe cooking medium and then upwardly out of the cooking medium towardsthe unloading station 18 where the slot 72 ends just before theturnaround sprockets 57 mounted on the idler shaft 56, FIGS. 8 and 12.At the unloading station 18, as the cross rods 61 of succeeding formingelements 16 traverse the turnaround sprockets 57, the forwardmostelement 16 accelerates away from the preceding forming element 16exposing the fried taco shell 170 which rests on the convex formingsurface or element 16a whereupon it may be engaged by the rotatingbrushes 74 and dislodged should it not fall itself by gravity onto theguide bar 79 which serves to guide the taco shell 170 onto the dischargeor take away conveyor 81 for packaging, inspecting and the like. The nowempty forming elements 16 return over the top of the frame 19 towardsthe forming station 13 for engaging and forming another tortilla into afried taco shell.

The taco shell fryer of the present configuration is adaptable from oneof several rows of forming conveyors 14 with each row having a capacityon the order of from 75 to 150 taco shells per minute. There is nointermittent motion in the several conveying systems employed in thetaco shell fryer 10 in contrast to the prior art systems and the presentdesign permits a long service life with low maintenance. A hood andhoist mechanism, well known in the art (not shown), would be supplied tothe unit 10. With substitution of a suitably configurated belt 21,tortillas may be accommodated with the present unit with the outer rangeof tortilla diameter being about 1/2 inch less in diameter than thevertical dimension of the forming elements 16. Thus a 6 inch diametertortilla may be accommodated. Tortillas 17 of smaller diameters may beaccommodated in diameters as low as 31/2 to 4 inches, with use of asuitable belt 21, the balance of the system remaining the same. Thiscontrasts with the taco forming apparatus of the prior art whichgenerally were limited to accommodating a single size of tortilla.

Although the particular apparatus disclosed here has been more or lessdirected to an embodiment for forming and cooking taco shells, it is tobe understood that the forms can be adapted to other shapes so as todeform any suitable configuration, and the invention is not limited toforming U-shaped articles. The embodiment shown and described above isonly exemplary. We do not claim to have invented all of the parts,elements or steps described. Various modifications can be made in theconstruction, material, arrangement and operation, and still be withinthe scope of our invention. The limits of the invention and the boundsof the patent protection are measured by and defined in the followingclaims. The restrictive description and drawings of the specific exampleabove do not point out what an infringement of this patent would be, butare to enable the reader to make and use the invention.

What is claimed is:
 1. A method of rapidly and continuously convertingsubstantially flat uncooked tortillas into cooked substantially U-shapedtaco shells, comprising the steps of: moving a plurality of closelyadjacent molds at a set rate of conveyance toward a forming zone, eachadjacent pair of said molds presenting cooperating convex leading andconcave trailing surfaces; quickly reversing the direction of movementof said adjacent molds so as to instantaneously create in rapidsuccession a series of repeating angular window-like openings betweenthe adjacent convex and concave surfaces of said closely adjacent molds;simultaneously moving a succession of relatively flat tortillas towardsaid forming zone at a rate of conveyance which is substantially greaterthen said set rate of conveyance of said molds; decelerating andarresting the movement of each of said tortillas as of the moment of itsarrival in said forming zone while simultaneously engaging opposed edgesthereof on fixed supports on either side of said forming zone;instantaneously contacting unsupported central portions of each of saidtortillas as they successively enter said window-like openings with aconvex leading surfaces of one of said molds so as to initially deformthe tortillas into said substantially U-shaped configuration; thereaftercontacting and holding the formed tortillas between cooperating convexand concave surfaces of said pairs of closely adjacent molds, as saidmolds commence movement in reverse direction away from said formingzone; and contacting said formed tortillas and molds with a heatedcooking liquid to a depth sufficient to effect cooking conversion ofsaid newly formed tortillas into taco shells while cooperativelyretaining the same between said closely adjacent molds through buoyancyof the tortillas within the cooking liquid.
 2. A method as in claim 1wherein the direction of movement of said closely adjacent molds isagain quickly reversed so as to again instantaneously create in rapidsuccession a series of repeating angular window-like openings to therebyfacilitate release of the cooked taco shells as end products.
 3. Amethod as in claim 1 wherein said step of reversing the direction ofmovement of said closely adjacent molds includes the step of impartingangular acceleration first to the concave trailing surface and then tothe convex leading surface of a pair of molds to form said window-likeopening, followed by the step of successively retarding the angularacceleration of first said concave trailing surface and then said convexleading surface of said pair of molds thereby bringing said pair ofmolds together in close adjacency for purposes of contacting and holdinga tortilla between them during said cooking step.
 4. A method as inclaim 1 wherein said step of contacting the unsupported central portionsof said tortillas in said window-like openings is carried out when saidconvex leading surfaces of the molds are substantially in a horizontalplane.
 5. A method as in claim 1 wherein said contacting and holding ofthe formed tortillas between the cooperating convex and concave surfacesof said pairs of closely adjacent molds during said cooking step iscarried out when said adjacent surfaces are substantially in a verticalplane.
 6. A method as in claim 1 wherein said succession of relativelyflat tortillas being moved toward said forming zone comprises a singlecolumn of substantially uniformly spaced tortillas.
 7. A method as inclaim 1 wherein said plurality of closely adjacent molds moving towardssaid forming zone comprise at least two lines of laterally spaced apartcolumns of moving molds and said succession of relatively flat tortillasmoving toward said forming zone comprise at least two lines of laterallyspaced apart columns of tortillas.
 8. A method as in any of theforegoing claims 1 through 7 wherein the cooking liquid is cooking oilwhich is maintained at a temperature within the range from 275° to 425°F.
 9. A method as in either claim 1 or claim 2 wherein the time periodof each of said rapidly repeating angular window-like openings is of theorder of about 0.225 seconds.
 10. In a method of rapidly andcontinuously forming and cooking substantially flat food products toachieve a final desired curvelinear shape thereof, the steps of: movinga plurality of closely adjacent molds at a set rate of conveyance towarda forming zone, each adjacent pair of said molds presenting cooperatingconvex leading and concave trailing surfaces which are substantiallynested within each other, quickly reversing the direction of movement ofsaid adjacent molds so as to instantaneously create in rapid successiona series of repeating angular window-like openings between said adjacentconvex and concave mold surfaces; simultaneously moving a succession ofsaid substantially flat food products toward said forming zone at a rateof conveyance which is substantially greater than said set rate ofconveyance of said molds; decelerating and arresting the movement ofeach of said substantially flat food products as of the moment of itsarrival in said forming zone while simultaneously engaging opposed edgesthereof on fixed supports on either side of forming zone; simultaneouslycontacting unsupported central portions of each said relatively flatfood products as they successively enter said window-like openings withthe convex leading surfaces of one of said molds so as to initiallydeform the substantially flat food products into the desired curvelinearshape; thereafter instantaneously and successively closing each of saidadjacent pairs of molds into the substantially nested condition tothereby contact and hold the formed curvelinear food products betweenthe cooperating convex and concave surfaces thereof; contacting saidformed curvelinear food products and molds with heated cooking liquid toa depth sufficient to effect cooking conversion of said food productswhile cooperatively retaining the same between said closely adjacentsubstantially nested molds through buoyancy with respect to the cookingliquid, said cooking continuing for a sufficient period of time toretain said food products in the desired curvelinear shape, thereafterremoving the adjacent molds and cooked food products from the cookingliquid and again substantially reversing the direction of movement ofsaid closely adjacent substantially nested molds so as to again effectinstantaneous opening of the same to facilitate release and removal ofthe cooked curvelinear food products as end products.
 11. A method as inclaim 10 wherein said step of reversing the direction of movement ofsaid adjacent molds includes the step of successively advancing andretarding adjacent portions of each of said adjacent pairs of closelyadjacent molds to thereby impart successive angular acceleration andretardation of each mold in sequence as it passes in reversing movementthrough said forming zone, to thereby achieve the instantaneousrepetitive forming of said angular window-like openings.
 12. A method asin claim 10 wherein said step of decelerating and arresting the movementof said substantially flat food products includes moving said foodproducts toward said forming zone at different rates of conveyancewherein said food products are moved at a first rate of conveyance whichis substantially greater than said set rate of conveyance of said moldsfollowing which the substantially flat food products are moved at asecond rate of conveyance which is also substantially greater than saidfirst rate of conveyance as well as substantially greater than the saidset rate of conveyance of said nested molds, said first and second ratesof conveyance of said food products being followed by said step ofinstantaneously arresting the movement of each of said substantiallyflat food products within said forming zone.
 13. In a method ofproducing taco shells by the use of interfitting male and female moldssubstantially U-shaped in cross section, in a vat of heated cooking oil,the steps of: advancing a plurality of substantially uncookedsubstantially flat tortillas in succession in a generally horizontalplane to a position of instantaneous support wherein the tortillas aresupported exclusively on the outer side margins of the same, engagingthe upper surface of each tortilla with a male mold and moving the malemold downwardly into the cooking oil and moving the tortilla therewithto cause the tortilla to be folded between its outer side margins ontothe male mold and to be carried into the cooking oil, almostsimultaneously engaging the lower surface of each tortilla with a femalemold as it is being moved from the horizontal plane by the male mold sothat the folded tortilla is carried between and supported by the maleand female molds during its travel through the heated cooking oil, andopening the male and female molds with respect to each other after thetortilla has been cooked in the heated cooking oil to permit cookedU-shaped taco shells to escape from between the male and female molds.